1. Field of the Invention
The present invention relates to an immunotherapy for patients with pancreatic cancer, employing an immunotherapeutic agent. The immunotherapeutic agent of the present invention comprises, as the main constituent, activated lymphocytes cultured from peripheral blood lymphocytes of the patients, wherein the activated lymphocytes contain high percentages of CD3− CD56+ NK cells.
2. Description of the Related Art
There are known immunotherapies for various types of cancers. In adoptive immunotherapies in particular, for instance, peripheral blood lymphocytes derived from a patient with cancer are activated with an antibody or antibodies, and expanded during culture, and then administered to the same patient, as an immunotherapeutic agent in a sense. The activated lymphocytes have various immunological functions. Among the activated lymphocytes are T and natural killer (NK) cells having cytotoxic activities against tumor cells.
NK cells are large granular lymphocytes which account for 10 to 20% of the human peripheral blood lymphocytes. Activated NK cells have non-specific cytotoxic activity or antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells, virus-infected cells, and the like. Different from T and B cells which develop into memory cells following the sensitization with antigens, such sensitization is not required for NK cells to attack tumor cells. Generally, NK cells attack tumor cells in a molecule-specific way immediately when directed to cancer cells. On the surface of activated NK cells, surface receptors inducing cytotoxic effects on tumor cells are expressed, such as NKG2D, TRAIL (TNF Related Apoptosis Inducing Ligand), and others.
Japanese Patent No. 3056230, Japanese Unexamined Patent Publication (Kokai) No. 2002-45174, Japanese Unexamined Patent Publication No. 2006-340698 and Japanese Patent No. 3951350 disclose culture methods by which various types of cells contained in the peripheral blood lymphocytes are selectively propagated. Japanese Patent No. 3056230, Japanese Unexamined Patent Publication (Kokai) No. 2002-45174 and Japanese Unexamined Patent Publication No. 2006-340698 relate to methods by which NK cells are propagated at relatively high percentages. Japanese Patent No. 3951350 relates to methods by which NK cells obtained are present at extremely small percentages or are hardly contained.